Process of carbonizing and hardening metal.



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, such eflects are impossible in steel hardened;

PROCESS 01F CARBONIZING AND HARDENING METAL.

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No Drawing.

To all whom it may concern:

'Be it known that T, "NELSON H. Bangs citizen of the United States,residing at 1216 Fifth avenue, in the city and county of San Francisco,State of California, have invented a new and useful Process ofCarbonizing and Hardening Metal, of which the following is aspecification. 1 g

This invention relates more particularly to the process ofhardeningsteel by the direct application of an oxy-acetylene' flame, incombination with othercarbonizing elements, and chilling.

In the following description a simple manner of putting this inventioninto practice will be disclosed, but ll do not wish to be understood asconfining this invention to the specific mode of operation, or theingredients set forth, as many variations may be introduced, well withinthe spirit of this invention as'defined in the claims succeeding thedescription.

The commercial type of oxy-acetylene apparatus delivers through ablow-pipe a flame, composed of acetylene gas and oxygen under pressure.The proportions of acetylene gas and oxygen can be varied by regulation, for the particularresults desired. In

the present invention the acetylene predominates, its high carboncontent being taken advantage of as a carbonizing agent.

The present process must not be confused with the well known process ofcase hardening, that consists in forming a superficial thin skin of hardmetal overlying the mass of metal'upon which it is formed. Casehardening serves very well under certain conditions, but practice hasdemonstrated that it will not for instance withstand heavy pounding androlling action without spalling orsplintering, the more ductile metalbeneath causing the hard skin to separate from the main body; 'a perfectdemonstration of the superficial character of case hardening.

The process, forming the subject of this invention, alters the physicalnature of the metal so treated, penetratingto-a considerable depth,preserving or increasing the toughness, while raising the temper orhardness to the maximum. Spalling y by this process.

The mode of operation in the practice at, this invention includes thedirect ap h tion to the surface of the nietal of the Specification ofLetters Patent.

Patented Dec. t2, 193W.

Application filed Ap1'i129, 1914. Serial No. 835,298.

the highly divided carbon contained within the acetylene and itsbyproducts of combustion are driven into the porous metal,

or absorbed by it, to the depth to which the temporarily increasedporosity extends, during the heating period. The absorption uof carbonand other hardening elements, during this period of superporosity can beaccomplished, by the surface application of commercial oyanid ofpotassium, followed by the application of a solution of salt .and coppersulfate in water. This solution should be applied as nearly as may be tothe surface of the heated metal, within the zone of the flame projectedagainst it. When the llmit of absorption has been reached, the processof hardening is completed by'the direct application of a chilling bath,such as brine or other mixtures flowed .over,"or ap plied to the heatedsurface. v

This hardening process may bet-localized that is to say a given areaof'the metal to be treated may be hardened, without altering thecharacteristics of the surrounding area; on the other hand the resultsare so uniform following" the use of this process, that a piece of metalprogressively treated will show no appreciable variation in hardnessthroughout the entire area treated at different times. The developmentof the oxy-acetylene art has not yet progressed to the point where aconsiderable volume of flame is available from a single blow pipe.

At present large areas are bein treated by this process by arranging theb o-wipes in gangs to increase the volume of ame to cover the desiredarea.

Having thus described this invention what I claim as new and desire tosecure by Letters Patent is:

1.. The process of earbonizing metals which includes heating the metalto a highly absorbent degreeby the direct application of an acetyleneflame.

3. In the process'ofhardening metal by carhonizing, the step consists inheatby the direct application of an oxy-acetylene flame, and applyingcyanid of potassium, and a solution of salt and copper sulfate, duringthe period of high temperature.

6. The process of treating metal which includes heating the metal to ahigh degree by the direct applicationof a high temperature flame, andapplying cyanid of potassium, and a solution of salt and copper sul--fate during the period of high temperature.

7. The process of carbonizing metal comprising heating the metal to ahighly absorbent degree by the direct application of an open acetyleneflame.

8. The process of carbonizing metal, which includes heating the metal toa temperature just short of the Welding temperature by the directapplication of an acetylene flame containing an excess of acetylene.

In testimony whereof, I have hereunto set 30 my hand this 22nd day ofApril, 1914.

NELSON H. BRAY. Witnesses:

BALDWIN VALE, A. J. HENRY.

